Inhibition of mouse fertilization in vivo by intra-oviductal injection of an anti-equatorin monoclonal antibody

The monoclonal antibody mMN9 recognizes an antigenic molecule, equatorin, which is localized at the equatorial segment of the mammalian sperm acrosome. Our previous results using an IVF system indicated that mMN9 blocked sperm-oocyte fusion. Antibody-containing and control solutions were injected directly into the right and left oviductal ampullae, respectively, of anaesthetized female mice to assess the effect of mMN9 on fertilization in vivo. After hCG treatment, the females were mated, and their oviductal eggs and implanted embryos were examined. mMN9 was retained in the oviductal lumen at 20 h after injection. The rates of fertilization and concomitant pregnancy were significantly lower than in the control side (P < 0.05). In addition, histological studies showed no evidence of pathological changes in the female reproductive tract after the injections. These results indicate that mMN9 inhibits mouse fertilization significantly under in vivo conditions and that this injection method should be useful for studying the effects of antibodies and agents on fertilization in vivo.     

Three-dimensional structure of phosphoenolpyruvate carboxylase: a proposed mechanism for allosteric inhibition

The crystal structure of phosphoenolpyruvate carboxylase (PEPC; EC 4. 1.1.31) has been determined by x-ray diffraction methods at 2.8-A resolution by using Escherichia coli PEPC complexed with L-aspartate, an allosteric inhibitor of all known PEPCs. The four subunits are arranged in a "dimer-of-dimers" form with respect to subunit contact, resulting in an overall square arrangement. The contents of alpha-helices and beta-strands are 65% and 5%, respectively. All of the eight beta-strands, which are widely dispersed in the primary structure, participate in the formation of a single beta-barrel. Replacement of a conserved Arg residue (Arg-438) in this linkage with Cys increased the tendency of the enzyme to dissociate into dimers. The location of the catalytic site is likely to be near the C-terminal side of the beta-barrel. The binding site for L-aspartate is located about 20 A away from the catalytic site, and four residues (Lys-773, Arg-832, Arg-587, and Asn-881) are involved in effector binding. The participation of Arg-587 is unexpected, because it is known to be catalytically essential. Because this residue is in a highly conserved glycine-rich loop, which is characteristic of PEPC, L-aspartate seemingly causes inhibition by removing this glycine-rich loop from the catalytic site. There is another mobile loop from Lys-702 to Gly-708 that is missing in the crystal structure. The importance of this loop in catalytic activity was also shown. Thus, the crystal-structure determination of PEPC revealed two mobile loops bearing the enzymatic functions and accompanying allosteric inhibition by L-aspartate.     

Elevated lead concentrations in Japanese ribs of the Edo era (300-120 BP)

Nineteen elements (Al, B, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Sr, Ti, V and Zn) were analyzed in excavated bone (rib) of the Edo era (a Japanese historical era, 300-120 BP (before present] from different burial conditions in Tokyo, and in contemporary Japanese bone (rib) obtained from autopsy cases. The elemental composition of the excavated bones varied according to their burial conditions. The concentration of soil-related elements such as Fe, Mn, Co and Ti in the bone was lowest in the samples in the "wooden coffin in a stone room", next lowest in the "funeral urn with mud", and highest in the "wooden coffin full of mud". The Pb concentration was higher in excavated bones than in contemporary bones and much higher, by as much as several tens micrograms/g, in the bones in the "wooden coffin in a stone room" and in the "funeral urn with mud". These results strongly support the notion that Japanese in the city of Edo were highly polluted by environmental lead.     

Nationwide survey on pediatric CT among children of public health and school nurses to examine a possibility for a follow-up study on radiation effects

A nationwide survey was conducted in Japan on paediatric CT among children of public health and school nurses to examine a possibility for a follow-up study on radiation effects. A survey questionnaire was sent out to 3173 public primary and junior high schools and 317 public health centres during October to December in 2009. According to the collected responses, 410 (16.2 %) children received the CT scans and the total number of CT scans was 585. Most of respondents expressed a high interest in radiation health effects and an intent to participate in the epidemiological study that will follow-up the health conditions of children. This study provides information to discuss the feasibility of the epidemiological study on health effects in children who received CT scans.     

Meta-analysis of second cancer risk after radiotherapy among childhood cancer survivors

Cancer risks among childhood cancer survivors following radiotherapy have not yet been well characterised in terms of radiation dose. A meta-analysis of studies on the excess relative risk per gray (ERR) of second cancer was conducted previously; unfortunately, the small number of eligible studies restricted quantitative evaluations. To solve this problem, a statistical method to calculate ERR estimates from other estimates was developed, and a meta-analysis was conducted again. The PubMed database was searched and 26 relevant studies were identified. ERR estimates were available in 15 studies, and for the other 11 studies, the regression-based model was used to calculate ERR estimates from other estimates. The overall ERR estimate was 0.40, which was much lower than that of atomic bomb survivors exposed as young children. Heterogeneity of the risk among studies was suggested, and a further study is needed to explore the heterogeneity among studies.     

Effect of grafted polymer species on particle monolayer structure at the air-water interface

We have studied poly(methyl methacrylate)-grafted(PMMA) particle monolayer systems at the air-water interface. In previous papers, we reported that PMMA chains grafted from particles (silica particle and polystyrene latex) were extended on water surfaces. Through observing deposited particle monolayers on substrates using SEM, we have confirmed that PMMA of large molecular weights were either dispersed or arrayed in structure with long inter-particle distances approximately 500 nm. In contrast, low molecular weight PMMA were observed to aggregate upon deposition. We speculated that the difference in morphology in deposited particle monolayers would be attributed to the affinity between the grafted polymer and the substrate. To examine the effect of this affinity three new polymer-grafted silica particles were synthesized with a fairly high graft density of about 0.14 approximately 0.43 nm(-2). As well as PMMA-grafted silica particles (SiO2-PMMA), poly(2-hydroxyethyl methacrylate) and poly(t-butyl methacrylate)--grafted silica particles (SiO2-PHEMA and SiO2-PtBuMA) were also prepared and subjected to pi-A isotherm measurements and SEM observations. These pi-A isotherms indicated that polymer-grafted silica formed monolayer at the air-water interface, and the onset area of increasing surface pressure suggests that the polymer chains are extended on a water surface. However, the morphology of the deposited monolayer is highly dependent on polymer species: SiO2-PHEMA showed that the dispersed particle monolayer structure was independent of grafted molecular weight while SiO2-tBuMA showed an aggregated structure that was also independent of grafted moleculer weight. SiO2-PMMA showed intermediate tendencies: dispersed structure was observed with high grafted molecular weight and aggregated structure was observed with low grafted molecule weight. The morphology on glass substrate would be explaiened by hydrophilic interaction between grafted polymer and hydrophilic glass substrate.     

Spatio-temporal distributions of accumulated charge density in atmospheric pressure dielectric barrier discharges

The effect of the secondary electron emission coefficient on accumulated charge density distributions in atmospheric pressure dielectric barrier discharges have been simulated using two-dimensional fluid model. Spatio-temporal distributions of accumulated charge density on each side of the dielectric have been examined. The differences of conventional waveforms of accumulated charge density and the simulated results were clarified. And when the dielectrics were negatively accumulated, charges were uniformly accumulated, while positive charges were not. Randomness of streamers' occurrence, and self-organized structures have been also examined by the accumulated charge distributions.